1. Introduction

Question 1

Define infection

Answer 1

The invasion of the hosts tissues by micro-organisms causing disease and pathological response by microbial multiplication, toxin production and the host and pathogenic responses.

Question 2

How do people contract infections?

Answer 2

From a source via an intermediary, physical contact or the environment, or via vertical transmission (mother to foetus).

Question 3

State the steps by which an infection occurs (5)

Answer 3

Exposure, adherence, invasion, multiplication, dissemination.

Question 4

What aids the process of infection?

What do pathogens use to help them infect?

Answer 4

Virulence factors

Question 5

Give examples of some virulence factors

Answer 5

Cytotixins
endotoxins
exotoxins

Question 6

Give some examples of exotoxins

Answer 6

cytolitic
AB toxins
super antigens
enzymes

Question 7

What can host cell damage be due to?

Answer 7

Direct damage or due to host immune response

Question 8

Name some pathogen related determinants of infection

Answer 8

Virulence factors
Inoculation size
Antimicrobial resistance

Question 9

Name some patient related determinants of infection

Answer 9

Site of infection
General state of health
Co-morbidities

Question 10

What should be asked when investigating an infection?

Answer 10

Is there an infection?
Where is it?
What is the cause?
What is the best treatment?

Question 11

Name some possible supporting investigations for infection diagnosis

Answer 11

FBC
C-reactive protein
LFTs
Kidney function tests
Imaging
Histopathology
Bacteriology

Question 12

Give some examples of bacteriology/virology investigations

Answer 12

Bacteriology:
Samples/specimens - swabs, fluids, tissues.
Microscopy, cultures and stain
Antibiotic susceptibility
Antigen detection
Nuclei acid detection

Virology:
Antigen/antibody detection
Viral nucleic acid detection

Question 13

How many categories of microbes are there?

Answer 13

4

Question 14

What are the categories of microbes?

Answer 14

Bacteria
Virus
Fungi
Parasites

Question 15

Describe a typical virus

Answer 15

Inside - nucleic acid (single or double stranded DNA or RNA)
Protein coat
Outer envelope sometimes
Spikes (targets for antiviral agents)

Question 16

What is used to classify viruses?

Answer 16

Baltimore Virus Classifciation

Question 17

What does the Baltimore Virus Classification do?

Answer 17

Classes viruses I to VII depending on the type of nucleic acid present.

Question 18

What is a bacteriophage?

Answer 18

A virus that invades and replicates within a bacterium.

Question 19

What is the structure of a bacteriophage?

Answer 19

Head, collar and tail
DNA contained within the head
Rest is made of protein

Question 20

What are the subcategories of prokaryote?

Answer 20

Eubacteria

Archeabacteria

Question 21

Describe a typical bacteria

Answer 21

Nucleoid (circular DNA)
Plasmids. Contained within the cytoplasm
Ribosomes

Plasma membrane and cell wall surround this.
May be encapsulated.
May have flagellum for motility
Pili

Question 22

Name the shapes of bacterium

Answer 22

Coccus/cocci
Spirillus
Bacillus/bacilli aka rods

Question 23

What staining technique are most bacteria classified by?

Answer 23

Gram stain

Question 24

Which gram stain comes out purple?

Answer 24

Gram positive

Question 25

What colour does gram negative stain come out?

Answer 25

Pink/red

Question 26

How are bacteria classified by O2 tolerance?

Answer 26

Aerobes or anaerobes. | May be obligate or facultative.

Question 27

What does facultative mean wrt o2 tolerance?

Answer 27

That the bacteria can thrive in either environment and survive.

Question 28

What are the two categories of fungi?

Answer 28

Yeasts and moulds

Question 29

What kind of organisms are yeasts?

Answer 29

Single celled

Question 30

What kind of organism are moulds?

Answer 30

Multicellular

Question 31

What are the 2 categories of parasites?

Answer 31

Protozoa and Helminths

Question 32

Example of helminths

Answer 32

Worms

Question 33

What kind of organism are Protozoa?

Answer 33

Single celled

Question 34

What are commensals?

Answer 34

Micro-organisms carried on skin and mucosal surfaces that can cause infection when transferred to another site

Question 35

What are commensals also known as in their natural location?

Answer 35

Mocrobiota

Question 36

What is true of microbiota?

Answer 36

Normally harmless and often even beneficial when in their normal environment

Question 37

How should an infection history be taken?

Answer 37

Symptoms - focal and systemic; severity; duration. | Potential exposures - food, activities, travel, antibiotics/drug hx